Acylazetine as a Dienophile in Bioorthogonal Inverse Electron-Demand Diels–Alder Ligation

Abstract

A new bioorthogonal N-acylazetine tag, suitable for tetrazine mediated inverse electron-demand Diels-Alder conjugation, is developed. The tag is small and achiral. We demonstrate the usefulness of N-acylazetine-tetrazine based bioorthogonal chemistry in two-step activity-based protein profiling. The performance of the new tetrazinophile in the labeling of catalytically active proteasome subunits was comparable to that of the more sterically demanding norbornene tag.